What might I do if that appears when I click the install file?
403 Forbidden means that there is a restriction in place that won't allow you to access the file. Check if there is an .htaccess file in place that won't allow you to access the file/folder. Make sure you have the minimum requirements (http://coppermine.sourceforge.net/faq.php?q=MinimumRequirements#MinimumRequirements) for coppermine. Contact your webhost if you have no clue.
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